/*
* author : Apiram
* created: 29.04.2023 02:41:46
*/
#include<bits/stdc++.h>
using namespace std;
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
int n,m,k;cin>>n>>m>>k;
vector<vector<int>>b(n),s(n);
for (int i = 0;i<n;++i){
for (int j = 0;j<k;++j){
int x,y;cin>>x>>y;
b[i].push_back(x);
s[i].push_back(y);
}
}
vector<vector<pair<int,long long>>>adj(n);
for (int i = 0;i<m;++i){
int x,y,cost;
cin>>x>>y>>cost;
--x;--y;
adj[x].push_back({y,cost});
}
long long ans = 0;
for (int j = 0;j<n;++j){
vector<vector<vector<long long>>>min_t(n,vector<vector<long long>>(n,vector<long long>(2,1e16)));
for (int i = 0;i<n;++i){
queue<int>q;
q.push(i);
min_t[i][i][0] = 0;
if (i == j){
min_t[i][i][1] = 0;
min_t[i][i][0] = 1e16;
}
vector<bool>hv(n,false);
hv[i] = true;
while(!q.empty()){
auto u = q.front();
q.pop();
hv[u] = false;
for (auto x:adj[u]){
bool need = false;
if (x.first != j && u != j && min_t[i][x.first][0] > min_t[i][u][0] + x.second){
min_t[i][x.first][0] = min_t[i][u][0] + x.second;
need = true;
}
if (x.first == j && min_t[i][x.first][1] > min_t[i][u][0] + x.second){
min_t[i][x.first][1] = min_t[i][u][0] + x.second;
need = true;
}
if (min_t[i][x.first][1] > min_t[i][u][1] + x.second){
min_t[i][x.first][1] = min_t[i][u][1] + x.second;
need = true;
}
if (need && !hv[x.first]){
q.push(x.first);
hv[x.first] = true;
}
}
}
}
for (int i = 0;i<n;++i){
if (i == j)continue;
for (int p = 0;p<k;++p){
if (min_t[j][i][1]==1e16 || min_t[i][j][1]==1e16)continue;
if (b[j][p]==-1)continue;
if (s[i][p] == -1)continue;
long long tt = min_t[j][i][1] + min_t[i][j][1];
ans = max(ans,(s[i][p] - b[j][p]) / tt);
}
}
}
cout<<ans<<'\n';
return 0;
}
